A source tells Us, "Jemima and Mike had the baby about a week ago. It's a boy named Memphis. The 'Girls' crew and Lena [Dunham] are so happy for her!" (Kirke and attorney Mosberg are already parents to daughter Rafaella, 2.)

"Girls" creator and Kirke's costar Lena Dunham hinted at the baby news on Nov. 21 by tweeting, "Yesterday was amazing. One of my friends had a baby, one got engaged and the doctor told me the bump on my tongue is nothing to worry about."

In an interview with Vulture earlier this year, Kirke revealed she hopes to have a big family in the future. "I want lots of kids and I want a garden and I hope to stay married to my husband," she said. "I hope to be working in some way that fulfills me."